Best Mature Crossover Fanfics
The 25 most-loved mature crossover fanfics on AO3, ranked by kudos. Crossovers answer fandom's eternal 'who would win' and 'would they get along' debates on the page, and the friction between universes generates stories neither canon could hold alone.
Top 25 Mature Crossover Fanfics
Ranked by AO3 kudos. Every fic on this list is tagged with crossover and rated Mature.
Atlas
by etymologyplayground
"Eh! 'Little brother,' what!" Wei WuXian says, mock-outraged. "I'm thirty-five!" (Sort of. He was born thirty-five years ago, anyway.) "You must be, what, twenty-five tops?""Nooo," Xie Lian says, smiling. "I'm eight hundred years old.""You don't look a day over four hundred," Wei WuXian says. "Serio
snipers solve 99% of all problems
by silentwalrus
Ed had thought, after the whole Promised Day, homunculus, entire country harvested for alchemical batteries thing, the batshit quotient of his life would have settled down some. He really ought to have topped out the meter with that one. But no. The bullshit is just getting started.“Are you fucking
My Soul, Your Heart
by Seriously_awkward_amy
Harry loses almost everyone he loves and discovers he is unable to follow them into the after life.He gets bored of moping in Grimmauld place so moves to the US, much to the thrill of MAUSA (who Harry firmly ignores). He settles in Forks, a quiet town that should give him the dull life he desires, t
Proof That Tony Stark Has a Heart
by orphan_account
With Voldemort defeated and Harry turning seventeen, the elder Weasley boys decide to give him a chance to be a normal teenager for a while; namely, by buying him a ticket to Malibu, California. But of course, Harry Potter can never do anything normally. Especially not once he meets Tony Stark in a
Butler Spider
by Danny_shells
Just before the battle with Thanos, Dr Strange pulls together enough power to send one person to a different dimension. A chance for that person to be safe from the destruction that Thanos was about to wrought on Earth. The group about to fight agreed that Peter Parker, for sheer virtual of being th
you are a paradigm
by 1electricpirate
Sometimes, only sometimes, when Sherlock is very far away and absolutely guaranteed not to return for at least three hours, John sits on the sofa and lets the tea make itself. In which John is (reluctantly) a wizard, Mycroft is (apparently) omniscient, and Sherlock is (surprisingly) oblivious.
Wind Hero: Wanderer
by PhantomFox19
While travelling through Sumeru, the Wanderer has been sent to the world of Japan, to the world of Superheroes and Villains. Will he find his way back or will he use this opportunity to start new life on a clean slate? The Wanderer in My Hero Acadamia
An Irrevocable Condition
by Maeglin_Yedi
Harry doesn't age while everyone he loves does. Sick of losing all those around him, Harry decides to move to a new world thanks to a ritual Hermione found. He ends up in a shithole without indoor plumbing where he meets a small but clever fellow named Bilbo Baggins who brings him along on a little
It’s gonna be the future soon, and I won’t always be this way
by Casimir
Something bad happens to Akabane Karma, something that wakes him up in a world completely unlike his own- and yet, here he is. Using the knowledge and skills Koro-sensei had given him and saving the world again.Vietnamese translation, by Minami093: https://my.w.tt/ZIrj12Ne2PCancelled after some issu
The Dragonborn Returns
by ChelleyPam
Six years ago Lord Stark’s bastard son vanished, caught up in a freak storm. Now the boy returns as a man, and he is much changed.
Pirate Heroes
by The_Mad_Mystic
Izuku Midoriya dies after the fight from Overhaul, successfully saving Eri. Before he passes on, something gives him an offer. A new world to explore, a goal, and friends both old and new await him. The good news, the pirates he ends up joining are good people. The bad news, they are probably as cra
Gods and Monsters
by reaperlight
It was not his intention to bring an innocent into his war with L. But then he couldn’t in good conscience leave him there to be returned to the cupboard under the stairs. Ryuk chuckled and clapped him on the back. “Happy Father’s Day. I’m sure Misa will be thrilled.”
Prodigal Son
by copperbadge
Bucky dies, but it doesn't take.
Shadow's Ward
by KimpatsuNoHoseki
Harry didn't know where the Shadows came from, just that they were always there for him. However, a chance meeting with others who have Shadows of their own, leads to a better life for him.
The Ophidiophobia Job
by Glinda
Leverage/Stargate SG1 Crossover. Team Leverage discover that their mark has access to lots of highly classified alien technology. Eliot calls in some help from a 'buddy in the business' and it turns out he worked for the Stargate programme. Conspiracies are discovered, bombs are defused, aliens are
MASTER OF DEATH
by mcsquared789
HARRY hated the deceptive idyll of Little Whinging — the oppressive sensation of being trapped somewhere he hated with people who wished he didn't exist, and an diminishing drivel of letters from his friends and family. Harry had witnessed death and horror, and yet he'd been left to rot here as if h
MHA: The Value of a Thief
by Taiman215
Heroes, righteous and hopeful...they are the ones that believe in and protect the peace. Villains, corrupted and chaotic...they are the ones that despise and wants to destroy this hero society. However there are those in between that work in the shadows to reform this society by changing the Hearts
Rising Blade, Falling Leaves (Fate x Naruto, EMIYA Centric)
by TheTangerineCat
He woke up in Konoha. A clan that wasn't his. A name he'd never owned. But that hill of swords remained beyond even the transcendence of worlds. She scurried out of the alley. Blonde hair, blue eyes, whisker marks on dirty cheeks. Some weird kid was watching her. One brow up. Like she was a peculiar
Celestial Traveler
by NovaSelene
The Celestial Grimoire and multiversal travel. Two powers that probably shouldn't have been given to a narcissistic, misanthropic teenager with massive trust issues.That said teenager would actually need everything the CYOA build she'd made at the end of their previous life had given her in order to
Red Flags & Rift Rags
by RevasLavellan
Welcome to Pop Idol: Rift Closure Edition, AKA Fade-Out Tour: Thedas, the smash-hit spin-off that no one asked for. The Veil is torn, demons are pouring out of the sky, and the Inquisition is scrambling to hold the world together. Into this mess drops Mira, idol-turned-rift-closer, armed with nothin
A place for the slaughtered lamb
by up_and_not_crying (saffrann)
To be loved is to be changed. That's the only truth she used to know as she climbed on and walked towards the altar, hoping to exchange her life for something worthwhile, the life of someone she loved.Bella did change and did die.Another eighteen-year-old lamb opened her eyes in hospital. Is she wil
The Two Commanders: Remastered
by Katieee
Fresh off destroying the Reapers, Commander Shepard falls into a strange, medieval world where people mistake her biotics for magic. No-one knows who she is anymore; beyond her title, neither does she. Knight-Captain Cullen has been a good templar for too long; being a good man feels far beyond reac
The Mix-Up
by comebackcas
Ciri was alone, miserable, and hellbent on avoiding her family when a strange young man dropped out of a portal in the woods.“Oh! Hello! I’m Jack.” Chasing Jack through a portal, Dean and Cas find themselves trapped in a bizarre universe with yellow-eyed hunters who call themselves Witchers and flir
Knights of Tal'Dorei
by Crimson_Soldat
After the destruction of the Star Forge, Revan has a vision of a planet under the influence of a dark Sith Lord. With the crew of the Ebon hawk at his side, they travel to Exandria to assist a group called Vox Machina in combating the dragons called the Chroma Conclave who may have connections to th
Bring The Light
by ms_katonic
Fourteen years after the fall of Corypheus, and the continents of Tamriel and Thedas discovering each other, the Dragonborn Inquisitor has gone on to become Empress of Tamriel, deal with her Dominion archrivals, and raise her also Dragonborn children, the oldest of which is now grown-up, a universit
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About This List
This list of 25mature Crossover fanfics spans 2,996,827 total words. Kudos range from 65 on the newest entries to 23,405 on the most established. Most entries are ongoing works, so subscribe on AO3 for update notifications. The most common rating is Mature (25 of 25 fics).
Recurring tags across this list: Crossover · Alternate Universe - Canon Divergence · Master of Death Harry Potter · Alternate Universe · Adventure.
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